Electronics Forum | Fri Jul 27 09:47:20 EDT 2018 | davef
Adding to Rob's suggestions ... One of the theories about voiding in thermal / ground pads of BTC is: Solder starts melting at the edge of the pad and moves inward towards the center of the solder mass. This traps flux volatilizes. So, there needs t
Electronics Forum | Fri Mar 17 21:38:55 EDT 2017 | jlawson
I think the main driver is MTBF data driven by the Car OEMS, mainly german makers pushing this onto suppliers in supply chain. Vacuum soldering and void reduction is a hot topic for the leading electronics suppliers in Germany at the moment. Is not r
Electronics Forum | Wed Mar 15 08:18:29 EDT 2017 | rob
It's well documented in higher power semiconductors where thermal interface materials are used, such as SIL pads, thermal grease etc. There are a couple of papers on the effects of voiding on MOSFET performance, but I haven't got around to reading
Electronics Forum | Wed Jun 03 13:56:09 EDT 2009 | mika
less total area of voids, which mean a much more strength in the joint and much easier to solder such a cooling pad grounded via vias, with this approach! The same goes for big cooling pads of let say Power transistors without any via etc. Always re
Electronics Forum | Wed Jul 03 09:47:39 EDT 2019 | SMTA-Pat
We have seen that vias included in the PCB under the thermal pad will give less voiding.
Electronics Forum | Thu Oct 25 13:35:47 EDT 2012 | davef
Here's a paper that may help http://www.ipcoutlook.org/pdf/assembly_challenges_bottom_terminated_ipc.pdf Temperature Impact * Profile didn’t have a significant impact on voiding. * Voids slightly increased with higher temperature. Reflow Atmosp
Electronics Forum | Thu Apr 23 07:51:45 EDT 2009 | scottp
Every paper I've seen published shows that BGA voids either have no effect or actually give a slight improvement. The one exception are voids with a root cause in bad incoming boards, such as champagne voiding where nearly the entire interface is go
Electronics Forum | Fri Jan 18 14:39:07 EST 2013 | davef
Main issues with LGA voiding are: * Design * Material selection * Thermal recipe For design, loo here http://blogs.smtnet.com/smt/other/qfn-btc-design-guidelines-thermal-pads-etc/ BR, davef
Electronics Forum | Wed May 22 19:47:30 EDT 2013 | anvil1021
Also, I was just thinking that most of the large companies we work with do not consider via drain an actual void. As a matter of fact our high dollar super fantastic Xray system actually has a switch to turn off the vias during void detection so that
Electronics Forum | Mon Feb 03 16:26:30 EST 2020 | stephendo
A few lifetimes ago I went to a seminar on reflow profiles. The speaker emphasized more than once that the cool down rate is important. Someone asked him about controlling the cool down rate and he acknowledged that you can't. And IIRC it was an ove
